Caspase inhibition protects from liver injury following ischemia and reperfusion in rats

Abstract

Normothermic ischemia and reperfusion of the liver results in microcirculatory failure followed by necrosis and cell death. Recently, another type of cell death, apoptosis or programmed cell death, was found to be activated during the early phase of reperfusion after liver ischemia. Caspases are cysteine proteinases specifically involved in the initiation and execution phases of apoptosis. The aim of this study was to demonstrate that inhibition of apoptosis by a specific inhibitor of caspases might protect the liver against ischemia/reperfusion injury. Rats were divided into three groups: group 1, control, PBS administration; group 2, Z-Asp-cmk (Z-Asp-2,6-dichlorobenzoyl-oxymethylketone) treatment; group 3, sham-operated control animals. Z-Asp-cmk (0.5 mg Z-Asp-cmk dissolved in 300 microl PBS solution containing 1% DMSO) was injected intravenously, 2 min prior to induction of 120 min ischemia. Survival rates were compared and serum activities of aspartate aminotransferases and alanine aminotransferases were assessed in the blood collected from the suprahepatic vena cava. Histology of the liver was assessed 6 h after the end of ischemia. Apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick end-labeling method (TUNEL method) and by electrophoresis for analysis of DNA fragmentation. Caspase activity was determined by measuring hydrolysis of the CPP32-like substrate Ac-DEVD-pNA and absorption of paranitroaniline. Z-Asp-cmk treatment significantly increased 7-day survival (95%) compared with that in nontreated rats (30%, P < 0.001). Serum activities of aminotransferases and the extent of liver congestion and necrosis were significantly (P < 0.001) decreased after treatment with Z-Asp-cmk. TUNEL-positive cells were detected 3-6 h after reperfusion in the control group. In Z-Asp-cmk pretreated rats, a dramatic decrease in the number of TUNEL-positive cells was observed. Analysis of DNA fragmentation of freshly isolated hepatocytes confirmed these results. Caspase activity was increased 3-6 h after reperfusion in the control group, but significantly (P < 0.001) decreased after treatment with Z-Asp-cmk. These findings demonstrate that liver injury following ischemia and reperfusion can be prevented by inhibition of caspases. Caspase inhibitors may have important implications for therapy in liver disease and after liver transplantation.

Cyclical ischaemic preconditioning modulates the adaptive immune response in human limb ischaemia–reperfusion injury

“…CD95 expression was more frequently found on the abundantly represented CD4 T cells and may be the pathway by which the systemic CD4 population is depleted by preconditioning. It should also be noted that a systemic release of ROS following reperfusion may contribute significantly to T cell apoptosis through its actions on mitochondrial caspase pathways also associated with CD9537, 38. IPC has previously been shown to have protective properties mediated through Fas inhibition on tissue cells exposed to ischaemia; its actions on lymphocytes as effectors of RI here suggest an additional beneficial mechanism39, 40.…”

Exaggerated up-regulation of tumor necrosis factor α-dependent apoptosis in the older mouse liver following reperfusion injury: Targeting liver protective strategies to patient age

“…TNFα binds to tumor necrosis factor receptor 1 (TNFR1) and activates the intracellular component of the apoptotic cascade, resulting in caspase 8 activation. Inhibition of TNFα signaling by TNFR1 knockout (KO) mice,14 deletion of Kupffer cells,17 inhibition of TNFα production by pentoxifylline,18, 19 and blockage of TNFα‐induced caspase activation20 have all been demonstrated to decrease reperfusion injury in animal models. Although TNFα clearly can drive HIRI, how or whether it contributes to the additional injury seen in older livers has not been examined.…”

Altered Zinc Homeostasis and Caspase-3 Activity in Murine Allergic Airway Inflammation

“…It has been suggested that increased release of serine proteases from neutrophils recruited during airway inflammation may be responsible for the detachment of human epithelial cells from their basement membrane (3). Because apoptotic pathways can be targeted by specific inhibitors (4,5), it is important to determine whether epithelial cells die by apoptosis resulting in shedding. Although it is a normal process, the regulation of apoptosis becomes altered in some chronic diseases, such as HIV and diabetes (6).…”